Constant-current regulator



H. G. HYDE "Oct. 27, 1931.

CONSTANT CURRENT REGULATOR Filed Nov. 1, 1929 5 Sheets-Sheet l INVENTOR ATfoRNEY 27, 1931. a. G. HYDE 1,829,484

CONSTANT CURRENT n mumg'on.

Filed Nov. 1, 1929 3 Sheets-Sheet 3 ATII'ORNEY Patented Oct. 27, 1931 UNITED STATES PATENT? OFFICE HAROLD G. HYDE, F MASURY, OHIO, ASSIGNOR T0 WESTINGHOUSE ELECTRIC & MANU- FACTURING COMPANY, A CORPORATION OF PENNSYLVANIA CONSTANT-CURRENT REGULATOR Application filed November 1, 1929. Serial No. 404,007.

My invention relates to constant-current regulating transformers of the movablewinding type and more particularly to means for supporting the movable windings thereof and guiding their movement.

A constant-current regulating transformer of the movable-winding type consists of relatively movable primary and secondary windings and a core structure providing a magnetic circuit inductively coupling them 'lransformers of the movable-windingtype, utilizing a counterwei ht for balancing the movable winding, have been employed 1n which the movable winding and its counterweight have been suspended by cords, chains, or other flexible members. In the movablewinding-counterweight type of construction, the movable winding is free to move vertically along the winding leg in response to the magnetic forces induced therein. If the axis of the transformer diverges an appreciable amount from the vertical, the movable winding will move laterally and come in contact with the winding leg of the core member and its movement along the winding leg which will thus be retarded, resulting in unsatisfactory operation. To obtain satisfactory operation of a transformer of this type, it is necessary to install it on a firm foundation and to have its axis substantially vertical.

'lransformers of the movable-winding type have also been constructed in which the movable winding is held in a frame work that is pivotally supported at one side of the core member. This pivoted construction requires longer coils, necessitating the employment of a greater amount of iron and copper than a construction in which the coils move at right angles to the axis of the core, thereby increasing its losses and lowering its efficiency, and requiring more space for its installation.

If the windings of a constant-current transformer are maintained parallel to each other in all positions, they do not have to be made as large for a given capacity, thereby using less copper and iron and operating more efficiently.

It is usual practice to mount constant-current transformers outdoors on poles or in under round vaults. For such installations, trans ormers should be rugged, require very little attention and be capable of satisfactory operation even if mounted at an appreciable angle from the vertical. For installation in an underground vault, they must be of comparatively small dimensions in addition to having the aforementioned attributes.

One object of my invention is to provide a transformer of the above-indicated character that shall be rugged, compact and economical of materials used and that shall require very little attention.

Another object of my invention is to provide a transformer of the above-indicated character in which the windings are maintained in substantial parallelism at all times.

A furtherobject of my invention is to provide a transformer of the above-indicated character that may be satisfactorily operated when inclined appreciably from the vertical.

A still further object of my invention is to provide a transformer of the above-indicated character that shall be suitable for mounting outdoors on poles and in underground vaults.

A still further object of my invention is to provide a transformer of the above-indicated character in which the movements of the windings shall be positively guided.

To achieve the objects of my invention, I propose to mount the movable winding in a rigid structure that is swung from a mechanically counterbalanced pivoted device, and to provide means for positively guiding the movement of the movable winding so that it shall be maintained parallel to the stationary winding and normalto the axis of the transformer throughout its travel.

'A better understanding of my invention may be obtained by reference to the accompanylng drawings and to the following detailed description:

Figure 1 is a perspective view of a constant-current regulating transformer embodying my invention;

Fig. 2 is a side elevational view of the transformer illustrated in Fig. 1;

Fig. 3 is a perspective view of a constantcurrent regulating transformer embodying my invention in another form;

Fig. 4 is a side elevational view of the transformer illustrated in Fig 3 and Fig. 5 is a erspective view of a constantcurrent regulating transformer embodying my invention in still another form.

In eneral, the embodiment of my invention i ustrated in Figs. 1 and 2 comprises a magnetic core '2, two windings 3 and disposed on the core, one of which is stationary and the other movable and mounted in a supporting structure or cradle 5 that is connected, near one end,to upwardly extending arms 21 which are attached, by means of a rod 6, to one end of a pivoted device 7 that is free to move about a supporting pivot 30. Near the opposite end of the cradle 5, rollers 8 are mounted which are free to roll upwardly along the track 9 that is curved to conform to the arc through which the rod 6 moves,

thereby maintaining the windings in parallelism.

The magnetic core 2 is laminated, as shown, and consists of two outer legs 10 and a central winding leg 11, forming a core structure of the well known three-legged type having two openings or windows 12 therein. Frame members 13 extend along the vertical edges of the core 2 and are bolted together or secured by any other suitable means, and are also employed to hold a support 14 for the pivoted device 7 which is disposed above the core 2. At the base of the core 2, plates 15 and angle irons 16 are aifixed to the frame members 13 to support the transformer structure.

The windings which are mounted about the central or winding leg 11 comprise a stationary winding 3 and a movable winding 1-. The stationary winding 3 is fixed about the winding leg 11 and rests on beams 17 which are secured to the angle irons 15 by bolts 18, and the movable windin 4 reposes in a cradle 5.

I The cradle 5 consists of two channel memhere 19 which extend through the openings 12 of the core structure and are maintained by the spacing members 20 in the proper spaced relation to carry the winding 4. One end of the cradle is sup-ported from the rod 6 by arms 21 that are attached by means of bolts 22 to plates 23, which, in turn, are rigidly attached to the channel members 19 by means nseaaea of bolts 24. A spacing member 25 is interposed between thechannel 19 and the plate 23 to allow space for the arm 21 to pass between them. A rod 26 extends between the arms 21 to maintain them in the desired spaced relation.

Near the opposite end of the cradle to that from which it is suspended, rollers 8 are mounted on the channels 19 to roll along tracks 9 which are attached to the frame members 13 and are curved in such manner that their radii are the same as that of the arc throu h which the rod 6 swings. To eliminate riction as the rolls 8 move along the tracks 9, the rolls are provided with ball bearings.

The pivoted lever device 7 comprises two arms 27. One end of each arm 27 is pivotally connected to the upwardly extending arms 21 by the rod 6, and a weight 28, adjustable by the addition of extra weights 29, is adapted to slide along the two arms 27 at the other end. The arms 27 are spaced some distance apart and are pivotally supported by the shaft 30 that is held by two upwardly extending members 31 forming apart of the support 14:. The weight 28 may be moved along the arms 27 by means of a hand wheel 32 that turns a threaded shaft 33 which extends through the weight 28. The shaft 33 is supported by bearings 34 heldby members 35 that extend between the arms 27. The weight 28 is employed to partially counter-balance the weight of the cradle 5 and the winding i and its value and position on the arms 27 may be varied to change the value of the current to be maintained in the secondary winding 4.

Cable conductors 36 and 37 are connected "to the stationary and movable windings, re-

spectively, and serve to connect the transformer to the outside circuits.

The operation of the transformer illustrated in Figs. 1 and 2 is as follows:

The stationary winding 3 may be either a primary or a secondary winding and, correspondingly, the movable winding 1 may be either a secondary or a primary winding. When the transformer is energized, the force of magnetic repulsion between the primary and the secondary winding forces them apart. When the magnetic repelling force is balanced by the force tending to keep the windings together, the current in the secondary winding will have its desired value. If the current in the secondary windingincreases for any reason, such, for example, as a decrease in the resistance of the secondary circuit due to a decrease in the load, the current in the secondary winding will increase the force of magnetic repulsion between the windings. The winding 4, therefore, moves upwardly against the force of gravity until the leakage magnetic flux between the primary and secondary windings incr ases to such value that the resulting magnetic forces between the windings a ain brin them to a balanced condition. T e secon ary winding will then have assumed such a new position that the current is again at its desired value. If the current decreases, the force of magnetic repulsion between the windings will be lessened, and the force of gravit will cause the winding 4 to move downwar 1y to a new balanced position.

The cradle 5 and the supporting arm structure 21 for supporting the movable winding form a rigid structure pivotally supported by the rod 6. A movement of the structure about the rod 6 is prevented by the arcuate track 9 and rollers 8, the rollers following arcs corresponding in radius, and direction from their centers, to the arcs described by the rod 6 in its movement about the shaft 30.- An arcuate movement is, therefore, imparted to the movable winding and this winding remains parallel to the fixed windim Fig. 2 illustrates the position of the mov able winding 4 in its lowest position and, by dotted lines, its highest position. It also shows the path taken by the roller 8 and the rod 6.

In the embodiment of my invention illustrated in Figs. 3 and 4, a laminated threelegged core 40, having windings 41 and 42 disposed on the central or winding leg there of, is employed, with end frames 44 affixed to. and extending upwardly along the vertical edges thereof, similarly to the core structure 2 described hereinbefore. At the base of the core member 40, angle irons 45 are secured to the end frames 44 and are utilized to support the transformer structure.

The windings 41 and 42 are each free to move along the winding leg 43 and they repose in superposed cradles 46 and 47, respectively, each of which is suspended at three points by a system of levers from a leve1= supportin structure 48 that is attached to the top 0 the core by means of angle irons 49. The cradles 46 and 47 are similar in construction to cradle 5 hereinbefore described.

The lever-supporting structure 48 comprises a plate 50 having L-shaped members 51, 52 and 53 secured thereto, and extending upwardly therefrom, the members 51 and 52 being secured to the plate 50 at one end and the member 53 at the other end. The L-shape members 51, 52 and 53 serve as supports for main lever arms 54, and 56, respectively, that support the cradles 46 and 47.

Each of the main lever arms 54 and 55 has an adjusting weight 57 adapted to slide thereon and guided in its movement by a weight guide 58. Each of the lever arms 54 and 55 and its weig guide 58 are connected together at their ends by triangularly-shaped members 59. The main lever arm 56 also has a movable adjusting weight 60 and, as illustrated, the lever arm 56 extends through the weight 60. Each of the weights-57 and 60 has set screws 61 to secure the weights in any desired position. It will be apparent that the manner of supporting the weight 60 may be similar to the manner of supporting weights 57 and vice versa.

' The winding 41 is supported, at one end, by the lever arms 54 and 55 and, at the other end, by the lever arm 56. A supporting arm 62 is connected at one end of each of the lever arms 54 and 55 comparatively near the supports 51 and '52, respectively, and is adapted to turn about the point 63.. The arms 62 depend from the lever arms 54 and 55 and are rigidly secured to one end of the channels 19 of the cradle 46, at the bases thereof, to form two suspension points for the cradle 46. A link member 64 is connected to one end of the lever arm 56, comparatively near its support 53, and is free to turn about the point 65. The link member 64 is attached to the other end of the cradle '46 through a clevis joint 66 bolted to a support 67 that is aflixed to the spacing plate 20 to form a third point of suspension for the cradle 46. The three points of suspension permit freedom of w1nding-move merlilt vertically but prevent movement latera y.

The winding 42 is similarly supported. The arms 68 are connected to the lever arms 54 and 55, at the opposite ends from which the arms 62 are connected, and are adapted to turn about the points 69. The arms 68 are rigidly connected to the end of the channels of the cradle 47 at the bases thereof and form two oints of suspension for the cradle 47 A linfi member 70 is rotatably connected to the lever arm 56 at 71 and is connected to the opposite end of the cradle 47, similarly to the link member 67, and it forms the third point of suspension for the cradle 47.

On each side of the core 40, an arm 72 is attached to the end frame 44 and projects therefrom, each arm acting as a support for auxiliary levers 73 extendin and rigidly secured, to the upper cradle 4 at the lower connectin point of the supporting arm 68. The auxiliary levers 73 are mounted parallel to the main levers 54 and 55 and have the same dimensions from their support to the cradle connection as that of the main levers, thereby permittin freedom of winding movement vertical y, but preventing endwise motion.

The points of suspension of the link members'64 and 70 permit the windings to move vertically but do not necessarily restrict movement laterally or endwise. The points of suspension of the su porting arms 62 and 68 ermit freedom 0 coil movement vertica lybut prevent lateral movement.

Conductors 74 and 75 connect the u per winding 42 to the terminal board 76, an the conductors 77 and 78 connect the lower winding 41 to the terminal board 79. The terminal boards 76 and 79 are attached to brackets 80 which extend outwardly from the end frames 44. Conductors 81 and 82, together with terminals 83, connect the windings of the transformer to the outside circuits.

The operation of the embodiment of my invention illustrated in Figs. 3 and 4 is as follows:

The windings and cradles are so arranged that the weight of the primary winding balances the weight of the secondary winding and the force of magnetic repulsion.

For the purpose of illustration, the winding 42 will be considered the secondary wind ing. When the winding 42 is forced away from, or attracted to, the primary winding 41 by the magnetic forces therebetween, the main lever arms 54, 55 and 56 are set in motion by the supporting arms 68 and the link member 67, and the auxiliary levers 7 3 are set in motion by the cradle 47. The movement of the main levers 54, 55 and 56 will set the to that of cradle 47.

As before described, all the link members and the supporting arms permit vertical movement of the cradles 46 and 47. Their movement will be substantially vertical in arcuate paths about the supp0rts'51, 52 and 53 as centers and will be prevented from moving laterally by the supporting arms 62 and 68 and endwise by the auxiliary lever 73, ex-

cept the path described by the arcuate movement.

The supporting arms 62 will move through such arcs that the winding 41 will always maintain a position parallel to its previously occupied position, thereby ensuring the maintenance of the windings 41 and 42 in substantial parallelism. The value of the current to be maintained and the .secondary winding 42 may be varied by changing the positions of the adjusting weights 57 and 60. y

In Fig. 5 of the drawings, I have illustrated another embodiment of my invention which differs from the embodiment illustrated in Fig. 1 principally in providing guiding links instead of the arcuate track and rollers for guiding the movement of the movable wind- Tn general, this embodiment of my invention comprises a magnetic core 90, a stationary winding 91 and a movable winding 92 disposed on said core, the movable winding being mounted in a cradle 93 that is connected, near one end, to an upwardly extending frame member 94 that is attached by means of a rod 95 to one end of a pivoted device 96 that is free to move about a supporting pivot 97. Auxiliary link members 98 are employed to guide the movement of the cradle memb cradle 46 in motion in a direction opposite The core is of the laminated three-legged type, as in the transformer of Fig. 1. End frames 99 andlOl extend around the core member 90 and are utilized to hold a supporting member 102 for the pivoted device 96. Angle irons 103 are secured to the base of the core member to support the transformer. The stationary winding 91 rests on beams 104, and the movable winding 92 reposes in the cradle 93,- similarly to the transformer of F ig. 1. The cradle 93 is similar in construction to cradle 5 hereinbefore described, except the channel members are maintained in the proper spaced relation by rods 105.

. The cradle 93 is supported from the rod by the frame member 94 which is of substantially U-shape. The arms 106 of the frame member 94 engage one end of the channel members of the cradle 93 and have openings therein through which the rod extends. Each of the rods 105 is provided with av nut 107 at each end which may be turned to rigidly clamp the arms 106 to the channel ers.

' The pivoted device 96 is of substantially U-shape and is pivotally supported by the shaft 97 that is held by the supporting member 102, the arms 108 of the pivoted device 96 being pivotally connected to the upper end of the frame member 94 by the rod 95. The pivoted device 96 also comprises a weight 109, adjustable by the addition of weights 110, and supported by a rod 112 that extends through the weight 109 and slots 113 in the arms 108. A threaded shaft 114 extends through the weight 109 at right angles'to the rod 112 and is fixed at oneend by a cross member 115 of the pivoted device 96. The position of the weight 109 may be adjusted by a hand wheel 116 that is attached to the end of the shaft 114. The weight 109 performs the same function as the weight 28 of 6n each side of the core 90, a link member 98 is attached to the frame member 99 and extends parallel to the arms 108 of the pivoted device 96 and is attached to the cradle 93 by means of pins 117; The link members 98 have the same dimensions between their connecting points as the dimension between the pivot point of the pivoted device 96 and the eonncctionpoint of the rod 95.

Cable conductors 118 are connected to the stationary winding. and the cable conductors 119 are connected to the movable winding 92. thus connecting the transformer to the outside circuits. Felt bumpers 121 are provided on the core 90 to protect the movable winding 92 in the event of a violent thrust against the core member.

This embodiment of my invention operates substantially as does the transformer illustrated in Fig. 1. The link members 98 guide the movement of the end of the cradle 93 and constrain it to follow a path similar to the path taken by the end of the pivoted device 96.

From the foregoing description, it will be readily appreciated that the windings of my transformer will be maintained in substantial parallelism, regardless of a departure from vertical mounting, making it particularly well adapted for mounting outdoors on poles and in underground vaults. Further, it will be evident that the transformer may be made more compact, resulting in a saving in materials and space required for installation, thereby effecting economies heretofore unobtainable with transformers of this type.

Since many modifications of my invention may occur to those skilled in the art, I do not wish to be limited otherwise than as set forth in the appended claims.

I claim as my invention:

1. In a constant-current transformer, a magnetic core having a winding leg, a plurality of windings encircling said winding leg and adapted to change their relative positions along said winding leg in response to magnetic interaction between the windings, mounting means for said windings, means for maintaining the planes of the windings substantially parallel and normal to the axis of the winding leg.

2. In a constant-current transformer, a magnetic core having a winding leg disposed along an axis thereof, relatively movable primary and secondary windings surrounding said winding leg, means for guiding the movement of the windings so that the axes thereof will remain substantially parallel to the axis of the winding leg.

3. In a constant-current transformer, a magnetic core having a winding leg, relatively movable primary and secondary windings disposed on said winding leg, said windings being mounted for movement in substantial parallelism and guidin means for maintaining the axes of the windings parallel to the axis of the winding leg.

4. In a constant-current transformer, a magnetic core member having a winding leg extending along an axis thereof and forming windows therein, a plurality of wind ings surrounding said winding leg and extending through said windows, one of said windings reposing in a cradle, said cradle being free to move along said leg from and toward the other winding in response to the magnetic forces between the winding, a lever pivotally mounted on the core, means depending from said lever and rigidly connected to one end of said cradle, sliding members attached to the other end of said cradle, means afiixed to the core and so constraining the movement of said sliding members that the two ends of the cradle describe similar paths and the windings are maintained in substantial parallelism and normal to the winding leg.

5. In a constant-current transformer, a magnetic core having a windin leg extending along an axis thereof and orming windows therein, a plurality. of windings surrounding said winding leg and extending through said windows, one of said windings reposing in a cradle, said cradle being free to move along said leg from and toward the other winding in response to the magnetic forces between the windings, arms aflixed to one end of said cradle and extending u wardly, an. oscillatable member secured to t 'e core member for ivotally supporting the upwardly exten ing arms, curved members attached to the core, rolling members attached to the other end of the cradle and adapted to coact with the curved members to guide the movement of said other end of the cradle to maintain the windings in substantial parallelism and perpendicular to the winding leg at all times.

6. In a constant-current transformer, a magnetic core having a windin leg extending along an axis thereof and orming windows therein, a plurality of windings surrounding said winding leg and extending through said windows, one of said windings reposing in a cradle said cradle being free to move along said leg from and toward the other winding in response to the magnetic forces between the windings, a member pivotally mounted on the core member, means de ending from said pivoted member and holding one end of said cradle, curved members attached to said core, rollers attached to the other end of said cradle and adapted to coact with said curved members, said curved members having such radii that the rollers describe arcs of the same radii as that of the are described by said ivoted member thereby to maintain the win ings in substantial parallelism and normal to the winding leg.

7. In a constant-current transformer, a magnetic core, a winding leg extending along the vertical axis thereof, primary and secondary windings surrounding said winding leg, a cradle for so supporting one of said windings that it is free to move toward and away from the other winding along the winding leg in response to the magnetic forces developed between the windings, a lever pivotally connected to one end of said cradle for guiding it in an arcuate path, and means for guiding the whole of said cradle in a similar arcuate path for maintaining the windings in parallelism.

8. In a constant-current transformer, a magnetic core having a winding leg portion, primary and secondary windings encircling said leg portion, one of said windings being fixed and the other being adapted to move along said winding leg from and toward the for guiding the movement of said end in an arcuate path and means associated with the other end of said movable winding for guiding the movement of said other end along an arcuate path similar to that described by the first-named end,

9. In a constant-current transformer, a magnetic core having a leg portion, two

. windings surrounding said leg portion, one

winding being stationary and the other winding adapted to move toward and from the stationary winding in response to magnetic impulses engendered therein, means affixed to one end of the movable winding for guiding said end in an arc, and means whereby the whole of said movable winding is moved to conform to the are described by the first-named end.

10. In a constant-current transformer, a core having a vertically disposed leg, a primary and secondary winding disposed about said leg, one of said windings being adapted to move away from and toward the other winding in response to the magnetic forces developed therein, a mechanically counterbalanced device pivotally affixed to the core and suporting'one end of the cradle for constraining said end to move in an are, means associated with the other end of the cradle for constraining said end to move in an are similar to the first-named are.

11. In a constant-current transformer, 11 core, a winding leg extending along the vertical axis of said core, primary and secondary windings reposing in cradles a'nd encircling said winding leg, said windings and cradles being free to move toward and away from each other along said winding leg, means for so constraining the movement of the windings as to maintain them in parallelism and normal to the winding leg comprising a plurality of pivoted members, one end of each pivoted member supporting one end of one cradle, the other end of the pivoted member supporting the opposite end of the other cradle.

12. In a constant-current transformer, a core, relatively movable primary and secondary windings reposing in cradles one above the other, means for maintaining the windings in parallelism and perpendicular to the core comprising two mechanically counterbalanced pivoted members, one end of each being affixed to the lower cradle and the other end being affixed to the opposite end of the upper cradle, a third mechanically counterbalanced pivoted member aflixed to the cradles in a manner opposite to that of the first-named pivoted members.

13. In a constant-current transformer, a magnetic core having a winding leg portion, primer and secondary windings encircling said winding leg and reposing in cradles, said cradles and windings being free to move away from and towards each other along said winding leg in response to the magnetic forces therebetween, means for so constraining the movement of the windings as to maintain them in parallelism and normal to the winding leg comprising a plurality of main levers pivotally supported above the core member, arms depending from both ends of each lever, one depending arm of each lever supporting one end of one cradle, the other depending arm of each lever supporting-the opposite end of the other cradle, and auxiliary levers extending from the core to one cradle having the same dimension from the attaching point to the cradle as the main lever arm from the pivot to the depending arm.

14. In a constant-current transformer, a magnetic core having a winding leg portion, relatively movable primary and secondary windings encircling said leg and reposing 1n cradles, the cradles being superposed on each other, the cradles and windings being free to move along the winding leg away from and toward each other in response to the magnetic forces therebetween, means for maintaining the windings in parallelism and perpendicular to the core comprising two mechanically counter-balanced levers having arms depending from the ends thereof, one arm of each lever being al'iixed to the lower cradle and the upper arm being atfixed to the opposite end of the upper cradle, a third mechanically counter-balanced lever having arms depending from the ends thereof and affixed to the cradles in a manner opposite to that of the first-named depending arms, and link members extending from the core to the upper cradle having the same dimensions from the point of support on the core to the cradle as the lever arm from the supporting point of the first-named levers to the firstnamed depending arms.

15. In a constant-current transformer, a magnetic core having a winding leg portion, a plurality of windings surrounding said leg portion, one of said windings reposing in a cradle and free to move along said winding leg toward and away from the other winding in response to the magnetic forces therebetween, a member pivotally mounted on the core, means depending from said pivoted member and holding one end of said cradle, a link member-extending from the core to the same end of the cradle as the depending means and adapted to constrain the movement of the cradle to follow that of the pivoted member.

16. In a constant-current transformer, a

otally mounted on the core, a supporting member depending from the end of said lever and attached to one end of the cradle for causing said end of the cradle to guide the movement of said end in an arcuate path, a'

link member attached to the core and extending to the same end of the cradle as the depending member and having the same dimension between attaching points as the distance between the pivot point of the lever and the depending member for guiding the cradle to move in an are similar to the end of the lever.

17. In a constant-current transformer, a

magnetic core having a vertically disposed leg member, primary and secondary Windings inductively upon said winding leg, a cradle for supporting one of said windings, said cradle-supported winding being free to move along the leg from and toward the other winding in response to magnetic impulses engendered therein, a mechanically counter-balanced device pivotally ailixed to the core and supporting one end of the cradle for guiding said end to move in an arc, means connected between the core and the same end of the eradle to constrain the cradle to move in an are similar to the are traced by the pivoted de vice.

18. In a constant-current transformer, a magnetic core. a winding leg extending along an axis thereof, primary and secondary windings upon said winding leg, a cradle for supporting one of said windings, said cradle being free to move along the winding leg toward and away from the other winding in response to the magnetic forces between the windings, and means for guiding said winding for movement in an arcuate path While maintaining its plane perpendicular to the axis of the winding leg comprising a lever pivotally mounted on the core member and cradle-supporting means pivotally connected to the lever and rigidly connected to the cradle.

19. In a constant-current transformer, a magnetic core, a winding leg extending along an axis thereof, primary and secondary windings upon said winding leg, a cradle for supporting one of said windings, said cradle being free to move along the winding leg toward and away from the other winding in response to the magnetic forces between the windings, and means for guiding said winding for movement in an arcuate path while maintaining'its plane perpendicular to the axis of the winding leg comprising a lever pivotally mounted on the core member, eradle-supporting means pivotally connected to the lever and rigidly connected to the eradle and a second means cooperating with said core and said cradle forguiding a point in the cradle along an arcuate path similar to that described by the pivoted connection of said lever to said cradle-supporting means.

20. In a constant-current transformer, a magnetic core having a winding leg portion, two windings surrounding said leg, one of said windings being stationary and the other reposing in a cradle, said cradle being adapted to move along said leg inresponse to the magnetic forces between the windings, a counterweighted lever pivotally aflixed to the core member, means for guiding the movement of said cradle in an arcuate path comprising cradle-supporting means extending between the lever and the cradle and means cooperatively related to the core and the cradle for directingthe movement of the cradle, said guiding means cooperating to maintain the windings in substantial parallelism and normal to the Winding leg.

21. A constant-current transformer comprising a magnetic core, having a winding leg, windings on said winding leg relatively movable in response to magnetic forces between the said windings, characterized by a cradle element for supporting one of the said windings in such a manner that it is free to move along the winding leg towards and away from the other winding, a lever member pivotally connected to one end of said cradle element for guiding it in an arcuate path and guiding means whereby the whole of the eradle element is constrained to move in a similar arcuate path whereby the said windings are maintained in parallelism, and normal to the winding leg.

In testimony whereof, I have hereunto subscribed my name this 22nd day of October,

HAROLD G. HYDE.

Oil 

